In many applications, including scientific, industrial, educational, medical and military applications, information received from a single source, from a single source at different times, or from multiple sources are provided on a video display. Various windowing techniques are available for permitting two or more of such images to be simultaneously displayed to either provide the user with additional information or to permit various comparisons to be made.
While existing systems of this type offer many capabilities, such systems normally have limited flexibility and lack various useful options. For example, most such systems are adapted to only receive information from digital sources and in particular digital sources which present the display pixel information in a particular format. These systems do not have the capability of mixing information received from both digital and analog sources, which sources may present the information in different formats, and to both store such information in a common memory and to simultaneously display such information on a single monitor, all in a manner transparent to the user. Such systems also frequently lack a capability for mapping received information in a flexible manner to obtain display levels and most such systems do not have the capability of flexibly color mapping images to be displayed, which images are in either color or black and white, with a capability for color mapping image frames being simultaneously displayed using different mapping guidelines for at least selected ones of the displays. Another limitation with most existing systems is that they do not have the capability of separating various types of information available in a single image frame and for simultaneously processing such different types of information in different ways with the results of such processing being simultaneously displayable either alone or in conjunction with other information.
Further, for maximum flexibility in displaying multiple images, it is desirable to be able to compress or crop images horizontally and/or vertically as they are being stored with little or no additional steps and to be able to easily crop stored images for display.
A need therefore exists for a method and apparatus for controlling the display of one or more image frames on a display device which provides enhanced capability and flexibility over existing systems. In particular, such capability is required in conjunction with medical ultrasonic scanning equipment which is adapted to receive both black and white tissue data and Doppler color flow data from a single ultrasonic scan, and may also receive information concerning prior ultrasonic scans on the same patient, or other information useful in the diagnosis or treatment of a patient, from a video recorder or other analog source in a standard composite video format rather than in a selected digital black and white or color format. In such an application, a need may exist for storing and/or simultaneously displaying the differently formatted inputs, for quantizing information received from scans for separating tissue and color flow data for display and analysis and for manipulating the color mapping of either the color flow data or the normally black and white tissue data to more clearly show information needed by the physician or other medical personnel utilizing the system.